TSP Calculator

A TSP calculator projects what your Thrift Savings Plan will be worth at retirement once agency money and compound growth are included. Example: a federal employee earning $80,000 who contributes 5% of pay from age 35 to 62, starting from a $50,000 balance at a 7% average annual return, is projected to reach about $1,099,591 - and exactly half of the money contributed along the way comes from the agency.

The Thrift Savings Plan is the defined-contribution piece of federal retirement, open to civilian employees under FERS and CSRS and to service members under the Blended Retirement System. It works like a large, unusually cheap 401(k): you choose a percentage of basic pay, the money goes into index-style funds, and under FERS or BRS your employer adds contributions of its own. What makes the TSP distinctive is not the math but the matching formula, which is fixed government-wide rather than negotiated employer by employer.

How the TSP agency match works

Under FERS and BRS there are two separate streams of employer money, and it helps to keep them apart:

• Agency automatic 1%: your agency deposits 1% of basic pay every pay period whether or not you contribute a cent yourself.
• Agency matching: on top of the automatic 1%, your agency matches 100% of the first 3% of pay you contribute, then 50% of the next 2%.

Written as a formula, the agency contribution as a percentage of basic pay is:

where C is your own contribution as a percentage of basic pay. The function stops rising at C = 5, where the agency contributes 1% + 3% + 1% = 5% of pay. Contributing 6%, 10% or 20% adds nothing further to the match. That is why 5% is treated as the floor for anyone eligible: the first five percentage points of your own money are the only ones that come with a guaranteed 100% or 50% return attached before a single dollar is invested.

Agency contributions by your contribution rate

The table below applies the formula above to an $80,000 basic pay salary. Read the last column as the total that lands in your TSP account in one year.

Two things stand out. Contributing nothing still gets you $800 a year, because the automatic 1% is unconditional. And the jump from 4% to 5% costs you $800 of pay but brings in $1,200 - $800 of yours plus $400 more from the agency. After 5%, every extra dollar is purely your own.

A fully worked example

Take a FERS employee, age 35, earning $80,000 in basic pay, with $50,000 already in the TSP, contributing 5% of pay, planning to retire at 62. Assume a 7% average annual return and 2% annual pay raises. That is a 27-year projection.

In year one you contribute 5% of $80,000 = $4,000, which is $153.85 out of each of the 26 pay periods. The agency adds the automatic 1% ($800) plus a 4% match ($3,200), so $4,000 of agency money joins your $4,000. Total deposits in year one: $8,000, or about $666.67 a month. With monthly compounding at 7%, the balance ends year one at roughly $61,876.

Each following year the salary grows 2%, so contributions grow with it: by year 10 the salary is about $95,607, you put in $4,780 and the agency puts in $4,780, and the balance is near $225,407. By year 20 the balance is about $605,273. At age 62 the projection lands at $1,099,591, made up of:

• $50,000 starting balance,
• $141,377 of your own contributions,
• $141,377 of agency automatic and matching contributions,
• $766,836 of investment growth.

The headline lesson: your own deposits are only about 13% of the final number. Agency money matches them dollar for dollar at a 5% contribution rate, and compounding does the rest of the work.

Projected balance by contribution rate

Same $80,000 salary, same $50,000 starting balance, 7% return and 2% raises, but run over 30 years from age 35 to 65. Only the contribution percentage changes.

Notice how the agency column stops growing at 5%: $162,272 is the ceiling no matter how much more you save. Notice too that the 3% row still receives $129,818 of agency money, because the automatic 1% plus a 3% match is 4% of pay even though you only contributed 3%.

What time does to the number

Contributing 5% of an $80,000 salary with 2% raises and the full match, starting from zero at age 30 and earning 7% a year, produces very different results depending only on how long the money stays invested:

Deposits roughly quadruple between 10 and 35 years, but the balance grows twelvefold. Growth passes contributions somewhere around year 20 and never looks back. This is why a new hire who starts at 5% on day one usually beats a colleague who waits five years and then saves twice as much.

2025 contribution limits

The IRS sets an elective deferral limit that caps what you personally can put into the TSP each calendar year. For 2025 that limit is $23,500. From age 50 you may add a $7,500 catch-up contribution, for a total of $31,000, and a special higher catch-up of $11,250 applies for ages 60 to 63, allowing $34,750. Agency automatic and matching contributions sit outside those numbers entirely, so a FERS employee at the limit still receives the full 5% of pay on top.

The calculator applies the correct limit for each projected year based on your age, which is why a high contribution percentage flattens out in the year-by-year table once the cap binds.

The front-loading trap

Because the match is calculated per pay period, hitting the annual limit early stops both your contributions and the match. Say you earn $180,000 and elect 20% of pay. Each of the 26 pay periods is $6,923.08, so you contribute $1,384.62 per period and cross $23,500 partway through the 17th one. For the remaining 9 pay periods nothing is withheld, so no match is paid: at 4% of $6,923.08 per period that is about $2,492 of matching forfeited in a single year. The automatic 1% keeps arriving, since it does not depend on your deferral. The fix is arithmetic, not strategy: choose a percentage that spreads your target evenly over all 26 pay periods.

How to use this TSP calculator

1. Retirement system: pick FERS or BRS if you receive agency or service contributions, or CSRS if you do not. Legacy military retirement behaves like CSRS here.
2. Current age and retirement age: the difference sets the projection length. FERS employees often model 57 to 62; the calculator accepts any span.
3. Annual basic pay: use base salary only. Locality pay counts as basic pay for civilians, but military allowances such as BAH and BAS do not.
4. Your contribution: enter a percentage of pay. The label shows what that is per pay period across 26 paychecks.
5. Current TSP balance: the amount in the account today, across traditional and Roth balances combined.
6. Expected return and pay raise: 7% and 2% are reasonable long-run placeholders. Lower both for a conservative view.

The projection updates instantly. Read the balance at the top, then check the first-year breakdown card to confirm the agency numbers, and scroll the year-by-year table to see when the balance crosses milestones that matter to you.

Who this calculator is for

• New federal hires deciding what percentage to elect in their first weeks on the job.
• Mid-career civil servants checking whether their current rate gets them to a target balance.
• Service members under BRS confirming they clear the 5% threshold for the full service match.
• Employees approaching 50 weighing whether catch-up contributions are worth the take-home pay.
• Anyone comparing federal and private-sector offers who wants to price the value of the agency match.

Key TSP terms explained

• Basic pay: the salary the contribution percentage is applied to. Overtime and military allowances are excluded.
• Elective deferral: the money you choose to have withheld from pay, subject to the annual IRS limit.
• Agency automatic 1%: the unconditional employer deposit, paid even at a 0% contribution rate.
• Vesting: the service time required to own the automatic 1% and its earnings, generally three years for most federal civilian positions and two years under BRS. Your own money and the match are yours immediately.
• Traditional vs Roth TSP: pre-tax now and taxed later, versus after-tax now and tax-free qualified withdrawals. Agency money always lands in the traditional balance.
• Lifecycle (L) funds: ready-made mixes of the individual TSP funds that shift toward conservative holdings as a target date approaches.

What changes the result the most

• Years invested: the strongest lever by far. In the table above, five extra years at the end added over $500,000.
• Assumed return: in the worked example, the balance runs $631,161 at 4%, $754,417 at 5%, $907,880 at 6%, $1,099,591 at 7% and $1,339,815 at 8%. A one-point change moves the result by roughly 20%.
• Reaching 5%: moving from 3% to 5% in the worked example lifts the projection from $868,460 to $1,099,591, and $28,275 of that gain is agency money you would otherwise never see.
• Pay growth: promotions and step increases raise every future contribution, since the percentage is applied to a bigger salary.
• Starting balance: money already invested compounds for the entire span, so a transfer-in or an old rollover matters more than it looks.

Practical tips

• Elect at least 5% from your first eligible pay period. Missed matching cannot be made up later.
• Raise the percentage with every step increase or promotion so the higher contribution never hits your take-home pay.
• Divide your annual target by 26, not by 12, when converting a dollar goal into a percentage.
• Re-run the projection at a lower return, such as 5%, and make sure the plan still works in the pessimistic case.
• Remember the TSP is one leg of a three-legged stool. Model the pension and Social Security separately, then add them.

Limitations and assumptions

• Returns are assumed to be constant. Real markets deliver good and bad years in an unpredictable order, and the sequence matters near retirement.
• Results are in nominal dollars, with no inflation adjustment. Subtract your inflation assumption from the return for a rough real-terms view.
• Vesting is not modeled. If you leave federal service before vesting, the automatic 1% and its earnings are forfeited.
• The 2025 IRS limits are held flat for all future years, although the IRS typically raises them over time, so long projections are conservative on that point.
• The projection shows a gross balance. Traditional TSP withdrawals are taxable as ordinary income, and fund expenses, though very low in the TSP, are not deducted.

How it compares to related calculators

This page answers "what will my TSP be worth?" Neighboring questions have their own tools. The 401(k) Calculator runs the same compounding math but lets you type in any employer match formula, so use it for a private-sector plan or a non-standard match; use this page when you want the TSP rules of 1% automatic plus 3-and-2 matching applied for you. The FERS Retirement Calculator handles the civilian pension annuity, and the Military Retirement Calculator covers BRS retired pay, both of which sit alongside the TSP rather than inside it. Add the Social Security Calculator for the third leg. For a broader, non-federal view of the same savings question, the Retirement Calculator and the Investment Calculator are more flexible, and the Roth IRA Calculator helps if you are saving beyond the TSP.

Sources

• Thrift Savings Plan - tsp.gov, official plan rules on agency automatic and matching contributions, vesting and contribution limits.
• Internal Revenue Service - 2025 elective deferral limit of $23,500, age-50 catch-up of $7,500, and the $11,250 catch-up for ages 60-63 (IRS Notice 2024-80).